This invention relates to a rotor that is mounted on a hub that is retained on an axle with an exciter ring attached to the rotor wherein the exciter ring remains substantially concentric to the axle whenever the rotor experiences thermal expansive changes resulting from a brake application such that information detected by a sensor regarding the rotative movement of the rotor is not effected by changes in a perpendicular relationship between the rotor and the hub.
It is common to provide a vehicle with an electronic control that includes means to detect rotation of the wheels. Information relating to the rotation of the wheels is most often used to effect a brake application of a wheel when information is sensed that may adversely effect the safety or operation of a vehicle. Some of the information is often obtained from an electronic device that detects movement of a rotor by sensing reluctance changes in an exciter ring attached to a hub, as illustrated in U.S. Pat. No. 3,793,545. A wheel for the vehicle is attached to the hub that is retained on an axle of the vehicle. This type structure functions in a satisfactory manner for most applications but in some vehicles the space for locating an exciter ring in the hub is limited and it was suggested the exciter ring could be relocated as an integral part of the rotor to detect rotative movement thereof as disclosed in U.S. Pat. Nos. 5,067,597 and 5,332,065. An integral exciter ring functions in an adequate manner under most operational conditions however under an extreme brake duty cycle during which friction members sequentially engage the rotor for a long period of time without a sufficient time to allow the rotor to cool between periods of engagement, the rotor will experience thermally expansion. This thermal expansion may cause a rotor to be skewed from a perpendicular to a non perpendicular alignment with the hub and effect the validity of some sensed information relating to the rotation of the rotor.